Printing device with stabilized printing electrode

ABSTRACT

A printing device for printing characters, composed of a matrix of dots, by means of an image electrode which is displaceable over an information carrier via a transport belt. The image electrode consists of a wire piece which is guided near one end in a slot-like guide and is fed to the slot-like guide via a curved guide having a path of decreasing width.

111 3,855,600 4 1 Dec. 17, 1974' United States Patent .1191

Potma 11/1956 Zabriskie............;..............

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[73] Assignee: U.S. Philips Corporation, New 1 York I I Primary Examiner-Bernard Konick Assistant Examiner-Jay P. Lucas 22 Filed:

ec 21, 1972 I Attorney, Agent, or Firm-Frank R. Trifari 21 Appl. No.: 317,412

Foreign Application Priority Data Jan. 28, 1972 ABSTRACT Netherlands....................... 7201224 I A printing device for printing characters, composed of a matrix of dots, by means of an image electrode which is displaceable over an information carrier via a transport belt. The image electrode consists of a wire piece which is guided near one end in a slot-like guide AmQC /S9 54 l 7 6 4%B 368 E B 7 4 HUSH n wam ME .E 4 7 u a W 0S M H n E .dwM mmw m v .m a mm .l .w UhF HUM 555 [.ll.

' and is fed to the slot-like guide via a curved guide hav- [56] References Cite ing a path of decreasing width.

UNITED STATES PATENTS 2,212,970 8/1940 346/74 S 10 Claims, 7 Drawing Figures PATENTEDBEEWW ,3',855,600.

' sum 155 IRINTING DEVICE WITH STABILIZED PRINTING ELECTRODE The invention relates to a printing device for printing images composed of dot-like or line-like elements, in

particular alphanumerical characters, on an informa tion carrier. A transport belt having at least one image electrode, sliding over the information carrier and displaceable along a counter-electrode, is provided for printing character elements on the information carrier which is displaceablealong the'said electrodes. The image electrode displacement is transverse to the direction of movement of the transport belt, the image elecis .used which comprises a system of five image electrodes. Such a printing head consists of a flat, flexible carrier of an insulating material on which five electrically conductive tracks are provided which constitute the image electrodes. The flexible carrier is bent to form a V-shape along a folding line which is transverse to its longitudinal direction. The V-shaped printing head is arranged to be detachable in a specially shaped opening in the transport belt. This opening has a rim which extends transverse to the longitudinal direction of the transport belt, and which takes along the printing head when the belt is moved. During printing, one half of the V is guided under pre-tension against the information carrier, while the other'half of the V is guided under pre-tension in a beam having a U-shaped section. The bottom of said beam isprovided with conductive strips which serve to energize the image electrodes.

1 One end of the electrically conductive tracks of the printing head then slides over the surface of the information carrier, while the other end slides over a conductive strip in the U-shaped beam.

A drawback of the described printing device is that both the manufacture and the mounting of the printing head on the transport belt are subject to very narrow tolerances. For example, so as to obtained proper prints,'the ends of the conductors on the printing head which slide over the information carrier must be accurately aligned, while this alignment must be as parallel as possible to the said folding line. The folding line and the rim of the opening in the transport belt must be at right angles to the printing line direction. In the case of an inclined folding line or rim of the opening, it can also occur that the ends of the conductors on the printing head which slide over the conductive strips in the U-beam are not pressed onto these strips under the same pressure, so that irregular wear occurs while the contact area is reduced at thesame time.

The invention has for its object to eliminate the said drawbacks.

FIG. 1 is a plan view of the relevant parts of a printing device according to the invention.

. FIG. 2 is a side view of theprinting device according to FIG. 1.

- FIG. 3 is a diagrammatic representation of the guiding of the image electrode in a printing device according to the invention.

' FIG. '4 is a bottom view of the guide for the image electrode shown in FIG. 3.

FIG. 5 shows a first embodiment of an electrode section of a printing device according to the invention.

- FIG. 6 shows a second embodiment'of an electrode section of a printing device according to the invention.

FIG. 7 showsa third embodiment of an electrode section of a printing device according to the invention.

The preferred embodiment of a printing device ac- '9, the belt 7 drives a pulley 13 which is also suspended in the frame 9. Arranged about the pulley I3 is a transport belt 15 which is further guided viaa pulley 19 which is suspended in a U-shaped frame 17. The frames 9 and 17 are connected to a support plate 21 (see FIG. 2). Arranged at the front of the surface formed by the transport belt 15 and the pulleys Band 19, is a container 23 with developing powder in which a paddle wheel 27 is suspended. The paddle wheel 27 is rotatable by means of a motor 25. Via a shaft 29, the container 23 is journalled in supports 31 which are mounted on the support plate 21.

Connected to the transport belt 15 is an image electrode 33 which consists of a piece of wire. The method of connection will be described hereinafter with reference to the FIGS. 5, 6 and 7. The image electrode 33 is guided ina slot-like guide 35 which will be described with reference to the FIGS. 3 and 4. Opposite to the image electrode 33, a counter electrode 37 is rigidly arranged. By means of rolls 39 and 41, an information carrier 43 (denoted by dotted lines) is guided over the counter electrode 37. The roll 39 is arranged such that the information carrier 43 is guided along a supply aperture 45 of the container 23 after having passed the electrodes 33 and 37. The described printing device is of the static type, which means that brief gas discharges are generated between image electrode 33 and information carrier 43, in order to provide a latent charge image on the information carrier 43 in the pattern of the characters to be printed. Therefore, such an electrical voltage difference is applied between image electrode 33 and counter electrode'37 in known manner at the printing instant, that the so-termed Paschen voltage is exceede'din the space, which is always present between image electrode 33 and information carrier 43. In this case, the information carrier 43 consists of a dielectric layer which is provided on a substratum having favorable electrical conductivity properties. As already stated, the container 23 contains a commonly used developing powder which is applied, by means of the paddle wheel 27, through the supply aperture 45 to the areas of the information carrier 43 where a latent charge image has been formed. The further processing of the information carrier is irrelevant in this context and will not be elaborated upon, and neither will be the device required for this process.

The slot-like guide 35 is situated in a beam 47 (FIGS. 3 and 4) which extends parallel to the printing line direction on the information carrier. The beam 47 (not shown in FIG. 2 for the sake of clarity) is connected to the support plate 21. On its left-hand side (FIG.3) the beam 47 is provided with a curved guide path 49 which encloses a wedge-shaped opening 51 in conjunction with pulley 19. At the area where the wedge-shaped opening 51 is narrowest, the guide path 49 changes over into the slot-like guide 35. The guide path 49 serves to stabilize the image electrode 33, which starts to vibrate due to the centrifugal force and vibrations in the transport belt 15. A vibrating image electrode 33 could giverise to irregular printing. Stabilization is effected in that the end of image electrode 33 lands in the guide path 49, and leaves this path only after the undesired vibrations have been substantially damped. This is the case near the transition from guide path 49 to the guide 35. The guide 35 prevents any lateral vibrations of the image electrode'33 from giving rise to irregularities in the height of the characters to be printed.

The beam 47 is provided on the one side of the guide 35 with a light source 53, and on the other side of the guide 35 with a photocell (FIG. 4) which is arranged opposite to the light source 53. It is obvious that the light source-photocell combination is arranged near the end of the guide path 49, so that the light beam is interrupted by an image electrode 33 which is no longer subject to vibrations. Instead of a photocell, another photosensitive member can be used such as, for example, a photodiode. It is alternatively possible to make use of a position indicator for the image electrode 33, which comprises a magnetic circuit with an air gap. When passing through the air gap, the image electrode, made of a magnetically conductive material, changes the magnetic resistance of the magnetic circuit. Interruption of the light beam starts the logic of the printing device by means of the photocell 55. This is effected upon each passage of image electrode 33. By starting the logic in the described manner, the beginning of a line on the information carrier is always printed at the same distance from the edge of the information carrier,

even if the speed of the transport belt 15 is not perfectly constant.

In the first embodiment of an electrode section illustrated in FIG. 5, the image electrode 33 consists of a U-shaped, scalene, electrically conductive piece of wire (FIG. 5) which is supported in the transport belt 15 of electrically insulating material. One end 57 of the image electrode 33 is guided in slot 35 of the beam 47, which is made of electrically insulating material, for example, wear-resistant synthetic resin such as nylon or epoxy resin. The other end 59 of the image electrode 33 slides over a contact path 61 of electrically conductive material which is provided on the beam 47. The end 57 slides over the information carrier 43 which is in electrical contact with the counter electrode 37. The information carrier 43 is composed of, for example, an electrically conductive layer 63 which is in contact with the counter electrode 37, and a dielectric layer 65 which is in contact with the end 57 of the image electrode 33. The contact path 61 is electrically grounded in a usual manner, whilst the counter electrode 37 is connected to a voltage at-the instant of printing vby means of a switch not showm I V The second embodiment of an electrode section which is shown in FIG. 6, comprises an image electrode 33 which is mounted on the transport belt 15 by means of two fixing blocks 6f7 and 69. The fixing blocks 67 and 69 are made of an electrically conductive material, for example, metal, and are connected to the transport belt 15 by means of an electricallyconductive glue. The transport belt 15 is made of an electrically conductive material in this case; The block 67 has a borehole 71 in which one end 73 of the image electrode 33 is inserted. A part 75 of the image electrode 33 is situated in a slot 77, and a part 79 in a slot 81. A part 83 of the image electrode 33 bears under pre-tension against the wall of a bore-hole 85 provided in the block 69. The part 83 is arranged in the bore-hole 85 via a slot 87 in the block 69. An advantage of the electrode section according to FIG. 6, is that a worn image electrode can be quickly replaced by a new one. Via the electrically conductive transport belt 15, the image electrode 33 is electrically connected to ground. This is possible, for example, by means of a commonly used slide contact against the pulley 19, (see FIG. 3) which is made of metal for this purpose. The counter electrode 37 (see FIG. 2) is then controlled by voltage pulses.

In the third embodiment of an electrode section which is shown in FIG. 7, the image electrode 33 is connected, via two electrically conductive blocks 89 and 91 on the transport belt 15, which is made of electrically conductive material, by means of an electrically conductive glue. The block 89 has a U-shaped slot 93, which is bridged by a bolt 95 which is screwed into the block 89 and about which a part 97 of the image electrode 33 is wound. The block 91 is provided with a bore-hole 99, the wall of which is engaged under pretension by both a part 101 and a part 103 of the image electrode 33. Theparts 101 and 103 can be arranged in the bore-hole 99 via a slot 105.

his to be noted that the-transport belt 15 (FIG. 3) can be provided with a number of image electrodes 33. The counter electrode 37 (FIG. 2) is then subdivided into a number of separately controllable electrodes. The beam 47 (FIGS. 3 and 4) which forms a guide for the image electrode 33 can be made as a single piece, or can be composed of parts. For example, the curved guide path 49 can consist of a separate part which is connected on the beam 47. In that case, it is possible to use different materials for the beam 47 and the guide path 49. The transport belt 15 can be completely, but also partly, made of metal, for example, a steel band. For example, it is possible to use a transport belt 15 which consists of a textile-reinforced synthetic resin material on which a conductive lacquer is provided, a

mylar tape on which a conductive material is vapor deposited, or a belt which is wound from steel wire with' epoxy as a bonding agent to which silver powder is added. In the first two cases, the transport belt 15 is connected to ground by means of a slide contact directly on the transport belt. The image electrode 33 can also be stabilized by making the electrode slide along a wall of the guide 35 under pretension. The guide path 49 can then be dispensed with.

Finally, it is to be noted that in a printing device according to the invention, not only the commonly used dielectric paper can be used, but also information carriers which consist of, for example, a non-transparent semiconductor layer on a base of material which contrasts therewith, a carrier which is impregnated in electrolyte in which pigment is formed, or a currentsensitive information carrier.

What is claimed is: t l. A printing device for printing images upon an information carrier, said images composed of-dot-like or v line-like elements, said printing device a base member;

a belt supported upon said base member for movement about a plurality of pulleys;

an image electrode comprising a wire-like conductive member extending generally radially from and supported by said belt, said image electrode movable with said belt; I

electrode guide meanssupported by said base member guiding said image electrode in a slot-like aperture during printing;

curved guide path means guiding said image electrode and having a curved guide path feeding the slot-like aperture of said electrode guide means for stabilizing the movement of said image electrode; and

a counter electrode supported by the base member and disposed opposite said belt, said information carrier passing between said belt and said counter electrode, and consequently between said image electrode and said counter electrode, when said image electrode is" transported by belt in juxtaposition to said counter electrode, said information comprising:

carrier thus receiving an electrostatic charge when said electrodes are adjacently disposed towards one another and a predetermined potential exists therebetween.

2, The printing device as claimed in claim 1 wherein the electrode guide means is provided'on one side thereof with a light source, and on the other side thereof, with a photocell which is arranged opposite to the light source.

3. The printing device as claimed in claim 1, wherein the image electrode comprises a U-shaped piece of wire supported by said belt, one leg of the U-shaped piece of wire being guided in said slot-like electrode guide means during printing, the other leg of the U- shaped wire being in electrical contact with a conductive portion of said electrode guide means.

4. The printing device as claimed in claim 1, wherein the belt at least partly consists of an electrically conductive material which is electrically connected to the image electrode supported by said belt.

5. The printing device of claim 1, wherein the guide path of said curved guide path means has a decreasing width as it approaches the slot-like aperture of said electrode guide means.

6. The printing device as claimed in claim 5 wherein the electrode guide means adjoins, near one end thereof, the curved path means for guiding the image electrode into said slot-like aperture.

7. The printing device as claimed in claim 1, wherein the image electrode isarranged under pre-tension in two holders which are supported by the belt.

8. The printing device as claimed in claim 7, wherein at least one of the holders is made of electrically conductive material and is electrically connected to the electrode.

2 UNITED STATES PATEN OFFICE CERTIFICATE OF CORRECTION I Patenc No. 8 r I b 7 December 17, 1974 rrmonopaus GERHARDUSY' po'rMA Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 24,- aft-er "photocell" insert ---55-- Signed'end sea1ed'this22nd day of April 1975.,

.1 I (SEAL) v Attestr I v v r I C. I-TARSHALL DANN RUTH C; MASON I I J Commissioner of Patents; Attesting Officer' I and Trademarks P0405 UNITED STATES PATENT OFFICE r /s 5 9 CERTIFICATE OF CORRECTION Patent No. 3855600 Dated December 17, 1974 I ntr(s) THEODORUS GERHARDUS POTMA It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 24, after "photocell" insert --55--.

Signed and sealed this 22nd day of April 1975.

(SEAL) Attest: I

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks 

1. A printing device for printing images upon an information carrier, said images composed of dot-like or line-like elements, said printing device comprising: a base member; a belt supported upon said base member for movement about a plurality of pulleys; an image electrode comprising a wire-like conductive member extending generally radially from and supported by said belt, said image electrode movable with said belt; electrode guide means supported by said base member guiding said image electrode in a slot-like aperture during printing; curved guide path means guiding said image electrode and having a curved guide path feeding the slot-like aperture of said electrode guide means for stabilizing the movement of said image electrode; and a counter electrode supported by the base member and disposed opposite said belt, said information carrier passinG between said belt and said counter electrode, and consequently between said image electrode and said counter electrode, when said image electrode is transported by belt in juxtaposition to said counter electrode, said information carrier thus receiving an electrostatic charge when said electrodes are adjacently disposed towards one another and a predetermined potential exists therebetween.
 2. The printing device as claimed in claim 1 wherein the electrode guide means is provided on one side thereof with a light source, and on the other side thereof, with a photocell which is arranged opposite to the light source.
 3. The printing device as claimed in claim 1, wherein the image electrode comprises a U-shaped piece of wire supported by said belt, one leg of the U-shaped piece of wire being guided in said slot-like electrode guide means during printing, the other leg of the U-shaped wire being in electrical contact with a conductive portion of said electrode guide means.
 4. The printing device as claimed in claim 1, wherein the belt at least partly consists of an electrically conductive material which is electrically connected to the image electrode supported by said belt.
 5. The printing device of claim 1, wherein the guide path of said curved guide path means has a decreasing width as it approaches the slot-like aperture of said electrode guide means.
 6. The printing device as claimed in claim 5 wherein the electrode guide means adjoins, near one end thereof, the curved path means for guiding the image electrode into said slot-like aperture.
 7. The printing device as claimed in claim 1, wherein the image electrode is arranged under pre-tension in two holders which are supported by the belt.
 8. The printing device as claimed in claim 7, wherein at least one of the holders is made of electrically conductive material and is electrically connected to the belt.
 9. The printing device as claimed in claim 8, wherein at least one of the holders is a U-shaped block having a detachable bolt which is screwed through legs of the U, part of the image electrode being wound about said bolt.
 10. The printing device as claimed in claim 8 wherein at least one of the holders has a bore-hole into which one end of the image electrode is inserted as well as a slot for holding an intermediate portion of the image electrode. 